there has been a high profile case lately where 3 men were released after spending a few decades in jail accused of murdering some young boys. one of them spent a ton of time in solitary confinement and now has major distance perception problems, since his eyes had only 6 feet of space to focus on for so long.
made me wonder if animals enclosed in the more opaque enclosures suffer the same thing eventually - it makes sense that they would. for this reason alone lately, i try to get them all out once a week. if you have enclosures that have clear fronts that they can look out of, i think their eyes are probably being fully exercised.
anyway, for multiple reasons, i think it makes good sense to let them roam a bit outside their enclosure.